Amplification of the Ohm Model I: dual monoblock or tri-amplification?

StuBotNYC

StuBotNYC

New Member
My good friend and I became familiar with the Ohm brand when he found a nice pair of C3's on craigslist that he recapped and refoamed. we threw everything at these beauties, Pioneer sx1010, SAE dual mono, my Sony 55es, and most recently a QSC 1400; they love power and are very sensitive to equipment changes such as preamps and cartridges, he loved his so much be bought Walsh 3's which are great for classical, and both are just great overall performers, we were soon fans of this made in the USA speaker builder from my home town of Brooklyn NYC.

So after being so impressed with Ohm speakers, I started lusting after the flagship Model I's with their 12" woofers front firing tweeter and upward firing 3way 8"woofer mid tweet and insane 1500 wpc capabilities, I was determined to blow my socks off with 70s rock.

I recently purchased a pair on eBay in need of tlc. and have it all coming within the next few weeks! Needs some scratches worked out and a driver that I bought and new grilles.

I am wondering if anyone has had experience with tri-amplification of the Model I, and any other amplification methods that these monsters may eat.

I am planning in the short run to use my Sony 55es until I can find and match another to do a dual monoblock setup at 4ohms 680wpc. I am also interested in maybe using my recently recapped and rechipped 90s Sony (very dynamic with great high frequency transients) for mid and trebble in a 4ch output mode and run a QSC for the in 2ch. for the bottom.

or... a monster 1600wpc 4ohm QSC OR Mackie in 2ch..? I hear that since the ohms can do a tri amp setup that there are great benefits to be had for clarity and minimized distortion between the drivers.


Any advice? also, will I need a crossover up front or use the one on board the Ohm Model I?

Thank you fellow gear fetishists.
 
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Wish I had more time to respond this morning.. Not sure how you would tri-amp. Played with bi-amping. Think you are probably better going with one big amp.

If you eventually upgrade all the drivers and get the sub-bass activators you will not need big power. I've powered mine since the upgrade with a 35 watt tube amp. Couldn't before the upgrade. Currently they are singing nicely with a Sansui AU-919.
 
Thanks Punker X!

I talked to John Strohbeen at Ohm today via email and he informed me the best way to get the most dynamic headroom and absolute best sound with the least distortion is to triamp. I will edit his responses and post them here for anyone else who needs information.

question Punker X, do you have any scans of manuals for the aohm Model I?
Believe it or not the CEO Mr Strohbeen doesn't either! He told me when they launch the new site it will have a forum to upload and share docs.
 
My first pair, back in the day, was triamped. I used an external crossover, can't remember what I did to the internals of the speakers - from the factory they are set up for biamping using the internal crossover.

I had boatloads of power available. They can take any amount of power, it seems, but one thing I noticed is that after a certain volume level you can throw more power at them, but they don't really seem to get any louder.

Now that I'm older and don't listen at such high volume levels very often, I've got another pair, and am quite happy with a single 210 wpc receiver powering them.

If I were you, I'd start with a couple of amps and use the biamp capabilities of the speakers. I think you can have a lot of fun with 250-300 wpc on the subwoofers and maybe 100 wpc for everything else.

If you're not happy with that, then find a huge power amp for the subs, move the 300 wpc amp to the mids, and use the 100 wpc amp for the highs. For that I'm pretty sure you'll need an external crossover.

Have fun, report back here with your results!

bs
 
I've had very good success passively vertically bi-amplifying the Model Ayes with a pair of Yamaha M-85s.
The M-85s employ handy left/right gain controls and allow me to adjust volume balance between lows and highs for any room acoustics anomalies.
The Model I is a wonderful vintage speaker:yes:
 
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oh wow...the wood! its beautiful!
your photo really show off the quality of the cabinets, can't wait to baby and restore mine, get new cloth from ohm, the SBA and get some quality caps in these under ohms' suggestions.

I am still awaiting shipment, labor day and personal finance prevented them from being at their new home back in the Tri State owned by an aging Brooklyn punk.

the plan as of now:
use Sony amp and not turn it up to fry it.
get a qsc amp at around 800 wpc (2ch@4ohms)

use Sony for bi amp with qsc.

move or get thrown out of garden apartment, buy house, move turntable and preamp to other side of room in brick and rubber audio cabinet, buy one more amp and crossover then get police visit.
 
bshorey said:
My first pair, back in the day, was triamped. I used an external crossover, can't remember what I did to the internals of the speakers - from the factory they are set up for biamping using the internal crossover.

I had boatloads of power available. They can take any amount of power, it seems, but one thing I noticed is that after a certain volume level you can throw more power at them, but they don't really seem to get any louder.

Now that I'm older and don't listen at such high volume levels very often, I've got another pair, and am quite happy with a single 210 wpc receiver powering them.

If I were you, I'd start with a couple of amps and use the biamp capabilities of the speakers. I think you can have a lot of fun with 250-300 wpc on the subwoofers and maybe 100 wpc for everything else.

If you're not happy with that, then find a huge power amp for the subs, move the 300 wpc amp to the mids, and use the 100 wpc amp for the highs. For that I'm pretty sure you'll need an external crossover.

Have fun, report back here with your results!

bs
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fantastic stories and advice.

considering how little information seems to be out there on this flagship master crafted home earthquake inducers, threads like these need to be out there. I will post every step of my new relationship with the Ohms from the moment I uncrate them from their trip from the deserts of Colorado.

please, anyone with Ohm model I or ayaes like previously called (great idea the name alone makes these hard to track), post photos, specs, manuals, schematics, experience with dampening materials, rewires, capacitor experiments.... anything.


let's have an epic ohm model I thread.:thmbsp:
 
Punker X said:
Wish I had more time to respond this morning.. Not sure how you would tri-amp. Played with bi-amping. Think you are probably better going with one big amp.

If you eventually upgrade all the drivers and get the sub-bass activators you will not need big power. I've powered mine since the upgrade with a 35 watt tube amp. Couldn't before the upgrade. Currently they are singing nicely with a Sansui AU-919.
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thanks Mike!
yes I have been considering the SBS's, and have my good friend recap them, maybe even do a little wiring upgrade someday. I am interested in the raw power high headroom aspect of the model I's capabilities, occasionally I have been let down with certain recordings on my klh's, so the model I choice is driven by sheer madness and I doubt I will be driving these down. I'd rather have my klh's being driven remotely in my bedroom for that kind of listening.
 
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11 years later and my Model I's are in the basement storage room :(, have one rubbing voice coil on my original woofers, can't bring myself to drop $500 on a new pair of woofers, all my other drivers seem okay. I really want to resurrect these, found a seller on eBay with two original 12', but again, dropping $300 on them makes me gasp- but I guess new woofers or replacements will cost more and not be original, so I answered my own question!

Want to recap and rewire these DIY if possible- I did move out of that garden apartment, have the house, would love to hear these again, especially since I bought two Urei 6900s to power these bad boys...

Any advice from I owners is still welcomed- anyone recap these? Take pictures?
 
Punker X said:
Wish I had more time to respond this morning.. Not sure how you would tri-amp. Played with bi-amping. Think you are probably better going with one big amp.

If you eventually upgrade all the drivers and get the sub-bass activators you will not need big power. I've powered mine since the upgrade with a 35 watt tube amp. Couldn't before the upgrade. Currently they are singing nicely with a Sansui AU-919.
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been a long road with these monsters! I ran them for a while, got new "cat proof" screens from Ohm, had a ceiling fall on them (an old non code compliant 60+ year old 3/4" fireproof sheetrock meant for industrial applications in a rental), discovered a woofer with a rubbing voice coil... and then purchased twin Urei 6290 amps to try powering them, the Ohms ended up in my basement storage awaiting attention, and the two amps power separate systems in the house.

I saw an auction for two originals in good shape visually (so is my busted one), price tag high enough to cause irritation in my spouse, just dropped $200 on a pair of ESS model seven (vII) that await pickup...

Some day all my busted gear will be playing delicious vinyl.

Urei 6290 PDF
 
It has been a long road! Maybe a long shot, but did you try rotating the woofer to see if that would fix the rub? If nothing, you could pull that woofer and try to replace the surround, try to fix it?
 
Did you try flipping your woofers 180 degrees. Some have had success and eliminated the rub. Mine rubbed 20 years ago and I sent them Ohm, for a full rebuild and sub-bass activators. Best upgrade you can do. Still going strong 20 years later.
 
Punker X said:
Did you try flipping your woofers 180 degrees. Some have had success and eliminated the rub. Mine rubbed 20 years ago and I sent them Ohm, for a full rebuild and sub-bass activators. Best upgrade you can do. Still going strong 20 years later.
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I do remember rotating them a few years back and at the time didn’t affect the rub, but maybe now years later I should just try them again and re assess; who knows maybe a few years later gravity will have done the trick?

My surrounds are good, if John was still alive they might still be available to rebuild my existing woofer, not sure if they still offer the service.
 
not sure if they still offer the service
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I actually talked with Evan about rebuilding my Aye subwoofers, not too long ago. They still offer the service. Ohm Acoustics headquarters moved to Connecticut after John's passing. According to their Facebook, they are moving again but haven't announced where yet.

But their service department is still listed as Tiffany Place in Brooklyn. They said that didn't change. Give them a call or an email. I'm sure they'd be happy to try to help. Even just troubleshooting.
 
MetalDaze said:
I actually talked with Evan about rebuilding my Aye subwoofers, not too long ago. They still offer the service. Ohm Acoustics headquarters moved to Connecticut after John's passing. According to their Facebook, they are moving again but haven't announced where yet.

But their service department is still listed as Tiffany Place in Brooklyn. They said that didn't change. Give them a call or an email. I'm sure they'd be happy to try to help. Even just troubleshooting.
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I had my both my Aye subwoofers reworked by Evan a few months ago and am very happy I did. I also purchased the SBA circuits which Ohm had updated and developed while making mine. I recently disconected them and find lower base without them. My room correction software also confirms this. Evan explained the base is extended with the SBA but the speaker is not designed to play below the port tuning frequency and the driver could be damaged. Not sure what to think there as my ears tell me something different.
 
johntheodore said:
I had my both my Aye subwoofers reworked by Evan a few months ago and am very happy I did. I also purchased the SBA circuits which Ohm had updated and developed while making mine. I recently disconected them and find lower base without them. My room correction software also confirms this. Evan explained the base is extended with the SBA but the speaker is not designed to play below the port tuning frequency and the driver could be damaged. Not sure what to think there as my ears tell me something different.
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How much did it cost to rebuild?
 
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